1. Field of the Invention
The present invention relates to a system designed for the utilization of heat produced in the combustion of fuels and the conversion of a portion of the produced heat into useful mechanical and electrical power for extracting usable power from heat produced from the combustion of biomass, agricultural waste (such as bagasse,) municipal waste and other fuels. The present invention also relates to a cascade power system where heat is derived from a hot flue gas stream by mixing the stream with a precooled or partially spent flue gas stream so that the mixed flue gas stream has a desired lower temperature for efficient heating of the working fluid without causing undue stress and strain on the Heat Recovery Vapor Generator.
More particularly, the present invention relates to a cascade power system for extracting usable power from heat produced from the combustion of biomass, agricultural waste (such as bagasse,) municipal waste and other fuels, where the system includes an energy extraction subsystem, a separation subsystem, a heat exchange subsystem, a heat transfer subsystem and a condensing subsystem, where a fully vaporized or superheated single stream is formed from two a fully condensed incoming working fluid streams via heat transfer from a combustion gas stream.
2. Description of the Related Art
In a previous application for a cascade power system, United States patent application Ser. No. 11/099211, filed Apr. 5, 2005, a system designed for the same purposes was introduced in several different variants. However, in all of these variants, two different turbines were utilized, i.e., a high pressure turbine for lean working solution and a separate turbine for rich working solution. Moreover, considering that the rate of expansion of the rich solution in this previous application was quite high, the turbine working with the rich solution would, in most cases, be a multi-stage turbine or in fact consist of two consecutive turbines.
Although several systems have been developed to extract energy from thermal sources using a multiple component working fluid including a cascade system utilizing different working solution compositions, there is still an need in the art for an improved energy extraction system, especially, a system in which the working fluid or solution expanded in a turbine is all of the same composition.